Off-shore pipelining and construction operations are often conducted with barges which are propelled or manipulated by anchor line propulsions systems.
In general, such anchor line propulsion systems are characterized by two alternately operable "spreads" of groups of anchors. Each such spread may include four anchors, each having an anchor line extending diagonally from an anchor line winch station located at one of the four barge corners.
Generally, one such spread of anchors is employed at a time to effect barge manipulation, i.e. by "pulling-in" on the forward anchors and "paying-out" on the stern anchor lines. While the anchor lines of one such spread are being manipulated to effect barge movement, the alternately operable spread of anchors is being repositioned to take over the propulsion operation in a "leap-frog" manner when the anchor lines of the first spread have been moved to the extremities of their operable positions.
The present invention deals with the problems entailed in the difficult off-shore operating environment in manipulating anchors to new positions so as to effect the leap-frog propulsion technique above described.
Heretofore, it has been the general practice for service vessels such as off-shore tugs to relocate anchors by engaging looped ends of pendant lines, each of which is supported at the water surface by an anchor buoy and extends down through the water body to an anchor. Generally, pendant lines are slideably supported by such anchor buoys so that, when a pendant line is engaged by a service vessel, the pendant line may be attached to a winch and drawn in. The drawing in of the pendant line exerts a disengaging force on the pendant line associated anchor and enables the anchor to be supported by the service vessel for relocation purposes.
Substantial difficulties have been involved in pendant line engaging and retrieving operations of the type heretofore noted.
It has been a general practice for crewmen to lean out over outboard portions of a service vessel and manually manipulate a hook, conventionally termed a "tail chain hook" into hooked engagement with the looped end of a pendant line supported by the floating anchor buoy. This engaging operation may be awkward, particularly when rough seas are encountered.
The potentially hazardous nature of this operation requires substantial precautionary measures in order to adequately protect the safety and well-being of crewmen engaged in the pendant line engaging and retrieving operation. Such precautionary measures may inherently slow and complicate anchor line relocating operations.
Moreover, the anchor buoy, which generally remains located adjacent the stern of the service vessel, during the pendant line retrieving operation, may cause damage to the hull of the service boat or may be damaged itself as a result of rough sea conditions.
This invention constitues a marked departure from the prior art practices noted above and is characterized by a technique for mechanically "forking" or retrieving pendant line supporting anchor buoy from a body of water, rapidly elevating the anchor buoy above deleterious wave action, and depositing the anchor buoy in a safe, substantially stabilized and immobilized position on a stern deck portion of the service vessel. At this location, crewmen may safely and more easily manipulate a pendant line loop into engagement with a hoisting drum so as to effect the hoisting or retrieving of the pendant line and thereby the hoisting of the anchor for relocation purposes.
These objectives are accomplished by a system for retrieving, securing, and launching an anchor buoy, this apparatus being operable in combination with
floating vessel means floating on a body of water, PA1 anchor pendant line hoisting means carried by the floating vessel means, and PA1 floating anchor buoy means, including pendant line means, usually slideably supported by the anchor buoy means, having an engageable loop or eye in its upper end, and extending downwardly to engagement with a submerged anchor. PA1 anchor buoy catching means, PA1 anchor buoy elevating means, and PA1 anchor buoy securing means. PA1 the anchor buoy means to move away from the substantially immobilized position generally toward the water body, and PA1 the anchor buoy means to be deposited in the body of water and freed from the floating vessel means.
The apparatus is characterized by, and comprises, a mechanism including
The anchor buoy catching means is operable to engage the anchor buoy means while the anchor buoy means is floating on the body of water.
The anchor buoy elevating means is operable to elevate the anchor buoy catching means, with the anchor buoy means engaged therewith.
The anchor buoy securing means is operable to move the anchor buoy catching means, with the anchor buoy means engaged therewith, toward a substantially immobilized position above the body of water.
The pendant line means is operable, with the anchor buoy catching means and anchor buoy means disposed in the substantially immobilized position, to be engaged with the pendant line hoisting means carried by the floating vessel means. The pendant line hoisting means, so engaged with the pendant line means, is operable to effect hoisting of the pendant line means.
The pendant line hoisting means is thus operable to effect the hoisting of the pendant line means and is further operable to permit th subsequent paying out of the pendant line means subsequent to this hoisting operation.
The pendent line means is operable to exert a pulling force on the anchor buoy means. This pulling force is operable to cause
In more specific and independently significant aspects, the invention involves apparatus concepts dealing with a composite slideable and pivotable mounting arrangement for the anchor buoy catching means an anchor buoy securing means, with the anchor buoy elevating means comprising a cable and sheave arrangement which is operable to effect a relatively rapid initial elevating movement of the anchor buoy catching means.
Other independently significant apparatus aspects of the invention deal with a service boat, deck mounted track arrangement which provides an immobilizing arrangement for the anchor buoy catching means and an anchor buoy clamping means which operates to clamp fore and aft portions of the anchor buoy means.
The invention further contemplates, as a independently significant concept, a releasable locking arrangement for releasably interlocking the anchor buoy catching and securing means. This locking arrangement may be advantageously combined with an automatically operable release mechanism. This latter mechanism releases the anchor buoy catching means from the anchor buoy securing means for movement at least partially into the aforesaid track means, this releasing action preferably being effected automatically in response to engagement of the anchor buoy securing means with a stern deck portion of the floating vessel means.
Still further independently significant apparatus aspects of the invention may entail wave action ameliorating, shock absorbing means for controlling and minimizing wave action induced forces, acting on the anchor buoy and anchor buoy catching means. With this shock absorbing mechanism there may be employed electromagnetic anchor buoy holding means carried by the anchor buoy catching means.
In describing the invention in greater detail, reference will be made, by way of example--but not by way of limitation--to a presently preferred embodiment illustrated in the appended drawings.